Is the NANOGrav signal a hint of dS decay during inflation?


Abstract in English

As suggested by the swampland conjectures, de Sitter (dS) space might be highly unstable if it exists at all. During inflation, the short-lived dS states will decay through a cascade of the first-order phase transition (PT). We find that the gravitational waves (GWs) yielded by such a PT will be reddened by subsequent dS expansion, which may result in a slightly red-tilt stochastic GWs background at low-frequency band, compatible with the NANOGrav 12.5-yr result.

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